The Difference Between a DTD and an XSD in XML

When it comes to XML, two commonly used schema definitions are Document Type Definition (DTD) and XML Schema Definition (XSD). The focus keyword for this interview question is XML schema.

DTD (Document Type Definition)

DTD is an older schema definition format for defining the structure and constraining the elements of an XML document. It uses a syntax more suited for simple validation requirements.

XSD (XML Schema Definition)

XSD, on the other hand, is a more modern and feature-rich schema language that provides more flexibility and control over defining complex data structures in XML documents. It allows for data types, namespaces, and more advanced validation rules.

Key Differences

• DTD is less expressive and powerful compared to XSD.
• XSD supports more advanced features such as data types, namespaces, and element grouping.
• XSD schemas are written in XML format, whereas DTDs use plain text syntax.